A disk drive is an information storage device. The most basic parts of a disk drive are an information storage disk that is rotated, an actuator that moves a slider carrying one or more transducers to various locations over the disk, and electrical circuitry that is used to write and read data to and from the disk. The one or more information storage disks are clamped to a rotating spindle. More specifically, storing data includes writing information representing the data to portions of tracks on a disk. The transducer includes two separate devices a write transducer that writes information representing data to the disk and a read transducer or sensor that reads information from the disk.
The slider is a small ceramic block that carries the one or more transducers. The slider is aerodynamically designed so that it flies over the disk. The slider is passed over the disk in a transducing relationship with the disk. Most sliders have an air-bearing surface (“ABS”) which includes rails and a cavity between the rails. When the disk rotates, air is dragged between the rails and the disk surface causing pressure, which forces the head away from the disk. At the same time, the air rushing past the cavity or depression in the air bearing surface produces a negative pressure area. The negative pressure or suction counteracts the pressure produced at the rails. The slider is also attached to a load spring which produces a force on the slider directed toward the information disk surface. The various forces equilibrate so the slider flies over the surface of the information disk at a particular desired fly height. The fly height is the distance between the information disk surface and the one or more transducing heads, which is typically the combined thickness of the air gap and lubricant film. This film eliminates the friction and resulting wear that would occur if the transducing head and disk were in mechanical contact during disk rotation.
Storing data includes writing information representing the data to the disk. In the past hard disk drives were designed with a single data capacity. For example, the hard disk drive capacity for an assembled hard disk drive was set at 1 terabyte. The capacity of the hard disk drive was not changed in the factory or in the field. If the hard disk drive was not able to meet the set capacity, the hard disk drive was reworked or scrapped.
In another scenario, when a hard disk drive did not meet the designed for capacity, the parameters of the drive were reset at the factory or manufacturing site to produce a drive with a lower capacity. For example, the data frequency would be lowered in a hard disk drive, making the bits longer in an on track direction, or the track pitch was increased (lowering the track density or widening the tracks). The lower capacity drive could then be sold at a lower price point. Lowering the capacity included lowering the number of physical block addresses (PBA) where data could be stored. Logical block addresses (LBA) were also lowered since LBAs are mapped to the PBAs. Disk drives generally leave the factory or manufacturing environment having a maximum capacity. This end LBA capacity does not appear to be increased nor is there a mechanism for allowing such an increase.